1. School of Mathematics and Computer Science, Wuhan Textile University, Wuhan 430073, P. R. China
2. Institute of Industrial Science, The University of Tokyo, 153-8505, Japan
3. Department of Gastroenterology, Graduate School of Medical Science, Kanazawa University, Kanazawa, Ishikawa 920-8641, Japan
4. Key Laboratory of Systems Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, P. R. China